ROCK STREAMS OF VETA MOUNTAIN 765 



this can not apply to the Veta Mountain rock-streams. It is also plain that 

 these rock-streams can in no way be due to glacial action, as no signs of 

 glacial action are to be seen within 10 or more miles. It is quite possible, 

 therefore, that rock-streams may occur in many other places, heretofore 

 unsuspected. 



MEANDERS AND SCALLOPS 

 BY MARK JEFFERSON 



{AJ)Stract) 



Meanders, or balanced swings in river courses, occur from source to mouth, 

 though most fully developed in the plains part. The embaymeuts or scallops 

 produced in their upper course by meanders that come in contact with the 

 bluff are of identical measurement with the meanders and serve to estimate 

 the ancient volume of the stream. 



BEACH CUSPS 

 BY MARK JEFFERSON 



(Abstract) 



Beach cusps are points of gravel or sand that occur at times on almost all 

 beaches where these materials exist. Perspective foreshortening gives them a 

 fictitious appearance of regularity. They are caused probably in various ways, 

 by waves that play squarely on shore, either under on-shore winds or in still 

 weather after storms, when the diminishing waves accommodate themselves 

 more and more to the shape of the bottom and the configuration of the shore. 



NORTH AMERICAN NATURAL BRIDGES 

 BY HERDMAN F. CLELAND 



Published as pages 313-338 of this volume. 



Discussion 



Dr. Horace C. Hovey remained that he had no doubt that there were several 

 different ways in which natural bridges might be formed, as had been so ad- 

 mirably explained by the speaker. For himself he had been most interested 

 in those found in caverns, or left as the strongest parts of cavern roofs, whose 

 weaker portions had fallen in. Of the latter, the Natural Bridge of Virginia 

 had long been considered an illustrious example. This theory was first ad- 

 vanced in Jefferson's Notes on Virginia, who credits it to Doctor Gilman, by 

 whom it was claimed that the valley, or canyon, through which Cedar Creek 

 flows was once a cavern, of which this great arch was the sole remnant. 

 Doctor Hovey had seen small underground bridges in parts of Mammoth Cave 

 and in some Virginia caves, particularly what is styled "AI Serat," in Jewel 

 Cavern, in the Green Briar Valley. 



A noble specimen of natural bridge-making abroad was seen in the Brama- 

 biau Cave, near where the Jurassic limestone seems to roll Mlie a billow 

 against the granite flanks of the Cevennes Mountains in France. The small 



LTIT — Bull. Geol. See. Aisr., Vol. 21, 1909 



